Refactor root element background painting

Source/core/layout/LayoutObject.cpp

Index: Source/core/layout/LayoutObject.cpp
diff --git a/Source/core/layout/LayoutObject.cpp b/Source/core/layout/LayoutObject.cpp
index ea3e8a38731fcb5579ab27e653bd98016a5963d9..29359f1ab3f57a73d2056df4d4c4a39c5f08efa9 100644
--- a/Source/core/layout/LayoutObject.cpp
+++ b/Source/core/layout/LayoutObject.cpp
@@ -3173,15 +3173,6 @@ void LayoutObject::setShouldDoFullPaintInvalidation(PaintInvalidationReason reas
         if (reason == PaintInvalidationFull)
             reason = documentLifecycleBasedPaintInvalidationReason(document().lifecycle());
         m_bitfields.setFullPaintInvalidationReason(reason);
-
-        if (RuntimeEnabledFeatures::slimmingPaintEnabled() && isBody()) {
-            // The rootObject paints view's background. We need to invalidate it when
-            // view's background changes because of change of body's style.
-            // FIXME: The condition is broader than needed for simplicity.
-            // Might remove this when fixing crbug.com/475115.
-            if (LayoutObject* rootObject = document().documentElement()->layoutObject())
-                rootObject->setShouldDoFullPaintInvalidation();
-        }
     }
 
     if (!isUpgradingDelayedFullToFull) {